1. Field of the Invention
The present invention relates to a transmitter and receiver for a high throughput wireless communication system using a multiple antenna, a method thereof, and a digital intermediate frequency (DIF) transmission signal processing method for the same; and, more particularly, to a transmitter and receiver for a high throughput wireless communication system using a multiple antenna which improves a transmission speed while lowering an error rate for using of a modulation method such as 64-Quadrature Amplitude Modulation (QAM) by dividing and processing a transmission band into a plurality of bands in order to raise signal processes and frequency efficiency on the multiple channel in a wireless communication system using the multiple antenna for high throughput data transmission, a method thereof, and a digital intermediate frequency transmission signal processing method for the same.
This work was supported by the IT R&D program for MIC/IITA [2006-S-002-02, “IMT-Advanced Radio Transmission Technology with Low Mobility”].
2. Description of Related Art
A next generation Local Area Network (LAN) provides a very high throughput multimedia service to terminals such as a laptop computer, a personal computer, and a Personal Digital Assistance (PDA) at 200 Mbps transmission speed in a region within a 100 m radius. Also, the next generation LAN provides a wireless network environment for forming a hot-spot, office networking and home networking.
Recently, wireless LAN technology is used for providing a wireless Internet service originating areas such as an airport, a hotel or a café. In particular, Republic of Korea enables forming a wireless home network at home in a format that a wired broadband subscriber network, e.g., Asymmetry Digital Subscribe Loop (ADSL), as well as a public network wireless LAN service are integrated with a wireless LAN system.
In 1999, standards of Institute of Electrical and Electronics Engineers (IEEE) 802.11b in a 2.4 GHz band and IEEE 802.11a in a 5 GHz band are established. As an 802.11b system is commercialized later, usage of the wireless LAN is activated. The wireless LAN is maintained in a personally used private network without a service provider at an early stage. Since 2002, a public network service is originated from some nations such as Republic of Korea and U.S.A and a range of the service is recently extending. As a product of 802.11a and 802.11g is introduced to the market, data of 54 Mbps are maximally transmitted.
In an IEEE 802.11n task group, a method for raising the maximum throughput of a Media Access Control (MAC) layer, which is not the throughput of the simple physical layer, by higher than 100 Mbps has been discussed. In other words, a discussion for improving throughput by simultaneously considering the physical layer and the MAC layer is in progress. In view of the physical layer, a method for improving frequency efficiency by using a multiple antenna, e.g., a Multiple Input Multiple Output (MIMO) system, a method for increasing a bandwidth, and a method for applying adaptive modulation are considered.
The MIMO system is a system which remarkably improves a data transmission speed by forming a plurality of independent fading channels by using a multiple antenna on a transmission/reception end and transmitting different signals for each transmission antenna. Accordingly, the MIMO system transmits much data without increase of the frequency.
However, there is a problem that the MIMO system is fragile to interference between symbols, which occurs in high throughput transmission, and frequency selective fading. In order to overcome this problem, an Orthogonal Frequency Division Multiple (OFDM) method is used together. The OFDM method is a modulation method which is the most proper to high throughput data transmission. In the OFDM method, one data sequence is transmitted through a subcarrier wave having a lower data throughput.
When the MIMO system is integrated with the OFDM system, the benefit of the MIMO system is employed and the shortcoming of the MIMO system is offset trough the OFDM system. The MIMO system generally has N transmission antennas and N reception antennas and a MIMO-OFDM system has a structure that OFDM technology is integrated with the above format of the MIMO system.
However, since the conventional MIMO system applies 2 or 3 transmission/reception end antennas and a bandwidth may be lower than 40 MHz, there is a shortcoming that a hundreds of Mega level transmission speed is a limit channel capacity. A Giga level wireless communication system has been discussed in a Very High Throughput (VHT) task group and a system having a larger bandwidth is required to be developed in the VHT wireless LAN technology.